Potato chips are among the most popular snack food. Unfortunately, most potato chips are cooked by deep frying in oil, as the deep frying process gives the potato chips its characteristic light-and-crispy texture. During the deep frying, the potato chips are subjected to a rapid rate of heating at high temperatures, which rapidly boils water out of the potato chip pores to produce a puffed and expanded tissue structure within the potato chips. It is this puffed and expanded structure that gives the potato chips its desired light-and-crispy texture. Because the deep-frying process also results in the inevitable uptake of the cooking oil by the potato chips, potato chips are often high in fat content. As a result, many seek to limit or avoid consumption of potato chips for health reasons.
One alternative to deep frying potato chips is to bake them. Baking, however, typically requires the use of oil to coat the cooking surface so as to prevent the potato chips from sticking to the pan or other cooking surface. Moreover, because the baking process is a significantly longer process than deep-frying, it does not rapidly drive the water out of the potato chip tissue pores as in deep frying. Thus, baked potato chips are typically denser in texture than deep-fried potato chips.
Another alternative to deep frying potato chips is to cook them in a microwave oven. Microwave energy cooks food differently from deep-frying or baking. Both the deep-frying and baking processes provide a high temperature atmosphere that impinges on the surface of the food, thereby cooking food from the outside in. Moisture is driven from the exterior of the food first and the heat transfer takes place from the periphery to the center of the food product.
In contrast, microwave ovens typically cook food from the inside out. This is because microwave cooking of foods is accomplished by high intensity, high frequency electromagnetic radiation that penetrates into the food product. Heating occurs when the food absorbs the electromagnetic energy and moisture is transferred from the interior to the exterior of the product due to the evaporation of free water contained therein. As a result, the middle of the food is typically heated before its surface.
One significant disadvantage of microwave cooking of foods is that it does not typically brown or provide a crispy texture to foods, as is often desired. Microwave cooking is typically perceived as producing soggy and unappealing texture. Thus, the conventional wisdom has been to apply an additional heat source to the exterior of food items cooked in a microwave oven to produce the desired browning or crisping of the food items.
To that end, susceptor materials have been developed and used as a cooking surface to brown and crisp food items, such as pizza dough and French fries. A susceptor is typically a thin film made of metallized film, ceramics or metals that absorbs and interacts with microwave energy to produce heat. Among the first microwave susceptors marketed were those from the 1980s in a product called McCain Micro Chips, which provided a susceptor sheet as a cooking surface for cooking French fries in a microwave oven.
One problem with susceptor materials, however, is that the amount of heat generated by the susceptor material surface cannot be readily controlled, thus resulting in burning of the food items placed thereon. Moreover, a layer of oil is required to cook items such as potato slices on susceptor material to prevent sticking. The burning and adhesion of delicate or thinly-sliced food items is particularly problematic, as the burning and adhesion of the food items to the susceptor cooking surface irreparably compromises them and makes them entirely unsuitable for consumption.